Optimization of color in the mechanochemical activation of clays

Abstract

The present invention relates to a method for the mechanochemical activation and simultaneous optimization of the color of mineral material, characterized in that the mechanochemical activation and simultaneous optimization takes place in a first high-energy mill (40), the mineral material being ground together with a solid reducing agent in the first high-energy mill (40).

Description

[0001] Color optimization in the mechano-chemical activation of clays

[0002] The invention relates to a method for color optimization in the mechano-chemical activation of clays.

[0003] Activated clays have established themselves as additives, particularly in the cement industry. The current method is drying and calcining the clays, i.e., thermal activation. This requires energy for heating, and excessively high temperatures can also cause further chemical changes that may be undesirable.

[0004] Due to the firing conditions during thermal activation in an oxidizing atmosphere, naturally occurring iron compounds in the clays are converted, particularly into red iron oxides. This results in a reddish coloration of the activated clays, which significantly reduces the market acceptance of cements produced with them. The iron content, or rather the content of iron in its strongly coloring trivalent oxidation state (Fe 3+), largely determines the color of a calcined clay. The color is an important quality parameter for the potential use of these activated clays as a component of the typically gray cement. In particular, lower-quality ("lean") clays can have Fe2O3 contents of an average of 2 to 9 wt.%. In the so-called "red clays," the Fe2O3 content can be as high as 15 to 20%. These high iron contents can lead to a very intense and usually undesirable red discoloration of the artificial pozzolan produced in this way and the composite cements made with it during calcination, while low-iron clays lead to a pinkish color.For this reason, in the calcination or post-calcination areas of plants for the production of calcined clays, for example, firing conditions with reducing gas atmospheres are established, specifically to achieve the conversion of Fe2O3 in red-colored minerals, such as hematite, into black magnetite Fe3O4. Establishing reducing firing conditions, in turn, requires readily combustible fossil and expensive, CO2-intensive primary fuels such as natural gas, crude oil, lignite, or hard coal. From a process engineering perspective, creating reducing firing conditions to change the color is actually the opposite of firing conditions for optimal fuel conversion.In particular, so-called secondary fuels require consistently oxidizing combustion conditions for effective firing, which in turn requires complex post-treatment of the trivalent iron species in order to eliminate or reduce the undesirable red coloration in the thermally activated clay.

[0005] WO 2017 / 008 863 A1 discloses a method and a plant arrangement for processing and activating a raw material.

[0006] EP 3 909 682 A1 discloses a method and a roller mill for thermomechanically activating a clay mixture.

[0007] DE 10 2015 106 109 A1 discloses a process for the tribochemical activation of binders and additives.

[0008] A general overview of the state of the art can be obtained, for example, from the following scientific publications:

[0009] Bolm, Carsten; Hernandez, Jose G. (2018): Mechanochemistry of Gaseous Reactants (Angew. Chem. Int. Ed, 58). Online verfügbar unter http: / / dx.doi.Org / 10.1002 / anie.201810902.

[0010] Fernandez, Rodrigo; Martirena, Fernando; Scrivener, Karen L. (201 1 ): The origin of the pozzolanic activity of calcined clay minerals: A comparison between kaolinite, illite and montmorillonite. In: Cement and Concrete Research 2011 (41 ), S. 113-122. DOI: 10.1016 / j.cemconres.2010.09.013.

[0011] Ilie, Biljana; Radonjanin, Vlastimir; Malesev, Mirjana; Zdujic, Miodrag; Mitrovic, Aleksandra (2016): Effects of mechanical and thermal activation on pozzolanic activity of kaolin containing mica. In: Applied Clay Science 2016 (123), S. 173-181. DOI: 10.1016 / j.clay.2016.01 .029.

[0012] Tole, llda; Habermehl-Cwirzen, Karin; Cwirzen, Andrzej (2019): Mechanochemical activation of natural clay minerals: an alternative to produce sustainable cementitious binders - review. In: Miner Petrol 2019 (113), pp. 449-462. DOI: 10.1007 / s00710-019-00666-y.

[0013] Tole, llda; Habermehl-Cwirzen, Karin; Rajczakowska, Magdalena; Cwirzen, Andrzej (2018): Activation of a Raw Clay by Mechanochemical Process-Effects of Various Parameters on the Process Efficiency and Cementitious Properties. In: Materials (Basel, Switzerland) 2018 (11). DOI: 10.3390 / ma11101860

[0014] DE 10 2017 114 831 A1 discloses a process for processing fly ash and a process for producing cement.

[0015] A manufacturing process for activated clays is known from CN 109 954 485 A.

[0016] CZ 307 528 B6 discloses a process for treating kaolin, clay or a mixture thereof.

[0017] An epoxy resin and its production are known from JP H08 67803 A.

[0018] From CN 111 362 602 A a process for changing the colour of clay-containing cementing material is known.

[0019] Clay activation with metal salts is known from WO 97 / 01614 A1.

[0020] A process for producing sludge powders is known from Rll 2 209 824 C2.

[0021] Since clays are a complex system (especially compared to the firing of limestone), different activation processes lead to different products (activated clays) with different properties. Likewise, the diversity of the clays used means that not every process is suitable for every clay. The object of the invention is to enable color optimization in a simple manner and thus, in particular, to enable the use of otherwise unusable clays with a high iron content.

[0022] This object is achieved by the method having the features specified in claim 1. Advantageous further developments emerge from the subclaims, the following description, and the drawings.

[0023] The method according to the invention serves for the mechano-chemical activation and simultaneous color optimization of mineral material. It is therefore a matter, on the one hand, of activating the mineral material mechano-chemically in a first high-energy mill, rather than in a thermal process. On the other hand, it is a matter of simultaneously activating the mineral material and optimizing its color, rather than carrying it out in a subsequent step, as is usual with thermal activation. The key is therefore simultaneous activation and color optimization in a single milling process and thus in a single machine unit. Mechano-chemical activation and simultaneous color optimization take place in a first high-energy mill. For this purpose, the mineral material is ground together with a solid reducing agent in the first high-energy mill.

[0024] Mechanochemical activation consists of three phases or stages: In the first stage, the particle size decreases (more or less linearly) with the energy input. Simply put, the more you grind, the finer the product becomes (Rittinger zone). However, there is a limit to this, a particle size that can hardly be exceeded. From this point on, you enter a second stage where the particle size does not change with further energy input (aggregation zone). In this stage, the crystallographic structures are destroyed by the breaking of atomic bonds; individual atoms or entire groups of atoms are replaced by other atoms or groups of other atoms. Particularly on the particle surfaces, the initial crystal structure, as well as the bond type and oxidation states of atoms, are altered due to high energy transfer and subsequent chemical reactions.For economic reasons, the transition from the first to the second stage is avoided in normal grinding, where only the creation of surface area is desired. However, this step is necessary for mechanochemical activation. If the energy input is increased even further, a third stage can be reached, where an increase in particle size can be observed again due to the agglomeration of nanoparticles (agglomeration zone). This has a positive effect on the workability of mortars and concretes made from cements based on activated clays. This zone is therefore even more likely to be avoided in normal grinding, as a better result in terms of particle size distribution can be achieved with less effort.

[0025] However, it has been shown that high energy inputs, i.e., in the second stage, lead to changes in the material itself. This, for example, in clays, just as thermal activation does, leads to activation, i.e., a reactivity that allows the material to be used as a binder component (and thus as a clinker substitute). Therefore, with such high energy inputs, subsequent thermal treatment can be dispensed with.

[0026] However, it has been found that the energy requirement for purely mechanochemical activation can be higher than that for thermal activation. Therefore, the process according to the invention initially appears to be disadvantageous compared to conventional thermal activation. However, it has been shown that the process according to the invention is advantageous, particularly for the activation of clays, despite the comparatively high energy requirement. Especially with complex starting materials such as clays, thermal activation regularly results in several negative effects. Firstly, it is known that, for example, substances can escape from clays in gaseous form at elevated temperatures, which require more complex exhaust gas purification, particularly if additional CC separation (carbon capture) is required in the future. This can be avoided by avoiding higher temperatures.Secondly, at elevated activation temperatures, color-imparting components, such as iron compounds, are often oxidized, which in the case of iron leads to an undesirable red coloration of the product. In fact, simultaneous grinding with a solid reducing agent even makes it possible to use already strongly colored materials, particularly those containing Fe2O3, such as clays known as "red clays," as starting materials and process them into a color-neutral product. Although this increases the energy requirement for the actual activation step of the process according to the invention, it simplifies exhaust gas treatment and eliminates a separate process step with subsequent reduction. The entire activation process for producing a marketable binder can thus be efficiently simplified. Furthermore, different clay minerals have different optimal activation temperatures.For example, minerals from the kaolin and chlorite groups are activated at significantly lower temperatures than minerals from the mica group (muscovite, illite, etc.). If the optimal activation temperature of kaolinite is chosen for thermal activation of clays containing minerals from these groups, minerals such as muscovite and illite will not be activated. However, if the significantly higher activation temperature of muscovite and illite is chosen for thermal activation, the formation of new mineral phases, particularly spinels, will lead to overburning of the kaolinite, resulting in deactivation. This differentiation of clay minerals with regard to the optimal activation temperature is not applicable to mechanochemical activation.

[0027] Color-providing components, such as iron compounds, are often oxidized at higher activation temperatures, which, in the case of iron, leads to an increase in the undesirable red coloration of the product. Unlike the thermal activation of clay, in which the clay minerals are dehydroxylated and the resulting water completely evaporates, the mechanochemical process according to the invention demonstrates that the water or hydroxyl groups of the clay minerals are retained in the mineral structure and made available for reaction, for example, with a solid metal such as aluminum powder or zinc powder. The hydrogen produced during this reaction enables the conversion of Fe2O3 to Fe3O4 in the clay minerals, particularly according to the following chemical reactions: 2 Al + 3 H2O -> Al2O3 + 3 H2

[0028] 9 Fe2Os + 3 H2— > 6 Fe3Ü4 + 3 H2O

[0029] Total: 2 AI + 9 Fe2Os — AI2Os + 6 Fe3Ü4

[0030] As can be seen from the reaction equations, this is an autocatalytic reaction. This means that the water required for the first reaction step is not consumed at all.

[0031] - According to the invention, the color optimization process is particularly efficient because the kinetics of the chemical reduction reaction of Fe2O5 to Fe3O4 are improved by the availability of the water molecules or hydroxyl groups required for the reduction reaction in the clay minerals. This effect is based on the high energy level during mechanochemical activation and the resulting surface chemistry. After thermal activation, however, the water or hydroxyl groups required for such reactions are not present. The high mixing effect of the material during mechanochemical activation due to the high speed of the stirrer in the first high-energy mill.

[0032] According to the invention, the mechanochemical activation of the mineral material results in an increase in the R3 value (7d) determined for the assessment of reactivity or pozzolanicity according to ASTM C1897-20 by at least 150 J / g, preferably by at least 250 J / g, compared to the starting material. The activation is thus sufficiently high to allow the activated materials to be used as cement substitutes (supplementary cementitious materials, SCM). The ASTM C1897-20 standard is a standard commonly used in the cement industry for investigating the reactivity of cement admixtures and for characterizing their setting behavior.

[0033] In a further embodiment of the invention, the grinding and mechanochemical activation is carried out with an energy input per grinding chamber volume of at least 100 kW / m 3 , preferably at least 200 kW / m 3A typical value for a ball mill, as an example of a fine mill, is usually around 20 kW / m 3 and thus significantly lower (and more energy-efficient). The grinding chamber volume is understood to be the volume available inside the first high-energy mill, i.e., the free volume when there is no material and, for example, no balls in the first high-energy mill. Components belonging to the mill, such as a shaft or stirring tools and the like, which are arranged movably inside, are therefore not included in the grinding chamber volume, since this volume cannot be occupied by material.

[0034] In a further embodiment of the invention, after milling, a size-selective separation into a coarse fraction and a fine fraction is performed. The fine fraction is returned to the first high-energy mill, and the coarse fraction is removed as product. For example, the separation is carried out using a classifier. In this case, the fine fraction is recirculated, since activation is associated with an increase in particle size. This differs fundamentally from the normal separation and recirculation in a mill, where the coarse fraction is normally recirculated.

[0035] In a further embodiment of the invention, the second size-selective separation is carried out such that the size limit between the second coarse fraction and the second fine fraction corresponds to the smallest particle size achievable with the second high-energy mill times a factor of 2.

[0036] In a further embodiment of the invention, the first high-energy mill is operated continuously. This means that both mineral material is continuously fed into the first high-energy mill and activated mineral material is continuously removed. Therefore, the first high-energy mill is preferably operated as a continuous mill with an inlet and an outlet.

[0037] In a further embodiment of the invention, the first high-energy mill is selected from the group comprising vibratory mills, planetary ball mills, and agitated ball mills. Preferably, the first high-energy mill is selected from the group comprising planetary ball mills and agitated ball mills. These mill types have proven particularly suitable for mechanochemical activation, since particularly high energy densities can be achieved with these mill types. A dry-operated agitated ball mill is particularly preferred as the first high-energy mill.

[0038] In a further embodiment of the invention, a stirred ball mill with a length-to-diameter ratio of 2.5 to 5 is selected.

[0039] In a further embodiment of the invention, the first high-energy mill is filled with grinding media to a filling level of 50 vol.% to 95 vol.%, preferably 60 vol.% to 70 vol.%. The bulk volume of the grinding media is related to the volume of the first high-energy mill. Since the filling level is around 64% for a simple bed and around 74% for a densest sphere packing, even a theoretical grinding media filling level of 100% results in a corresponding free space, which can be occupied, for example, by the mineral material to be activated. However, since the filling level of a grinding media bed depends extremely on the shape and uniformity of the grinding media, it is practically easier to relate the grinding media filling level to the bulk volume and not to the actual (filled) volume.

[0040] In a further embodiment of the invention, grinding media are selected from iron or an iron alloy, or from aluminum or an aluminum alloy. Preferably, grinding media are selected from iron or an iron alloy. In particular, grinding media are selected from steel.

[0041] In a further embodiment of the invention, ceramic grinding media are selected.

[0042] In a further embodiment of the invention, grinding media with a diameter of 1 mm to 10 mm are selected. In a further embodiment of the invention, the agitator ball mill is operated at a peripheral speed of 2 m / s to 6 m / s, preferably 3 m / s to 5 m / s, particularly preferably 3.5 m / s to 4.5 m / s.

[0043] In a further embodiment of the invention, the agitator ball mill is operated with a gas volume flow and a material flow. The ratio of gas volume flow to material flow is adjusted such that the ratio of gas volume flow to material flow is between 0.0001 m 3 / kg and 5 m 3 / kg, preferably between 0.1 m 3 / kg and 2 m 3 / kg.

[0044] In a further embodiment of the invention, the mineral material is dried before being introduced into the first high-energy mill and comminuted to a residual moisture content of less than 1 wt.% and a grain size of less than 2 mm.

[0045] In a further embodiment of the invention, the mineral material is selected from the group comprising clay, ash, in particular fly ash, belitz cement clinker, old concrete fines, slag, phyllosilicates, and tectosilicates. Particularly preferred as the mineral material is clay or a mixture of clay and one or more other materials selected from the group comprising ash, in particular fly ash, belitz cement clinker, old concrete fines, slag, phyllosilicates, and tectosilicates, as well as limestone.

[0046] In a further embodiment of the invention, the mineral material is mechano-chemically activated together with 0.1-50 wt.% quartz or corundum.

[0047] In a further embodiment of the invention, the material is examined after activation and color optimization to determine the activation. For the examination, one or more methods are selected from the group comprising IR spectroscopy, RAMAN spectroscopy, X-ray diffraction analysis, heat flow calorimetry, thermogravimetry, scanning electron microscopy, particle size and / or particle shape analysis, NMR spectroscopy, and colorimetry. Particularly preferred for the examination are one or more methods selected from the group comprising IR spectroscopy, RAMAN spectroscopy, X-ray diffraction analysis, heat flow calorimetry, and colorimetry.

[0048] In a further embodiment of the invention, a gas is selected and used as the gas flow through the first high-energy mill, which comprises one or more gases selected from the group comprising nitrogen, argon, carbon dioxide, water vapor, carbon monoxide, hydrogen, hydrocarbons, in particular methane, ethane, propane, and butane. Particularly preferably, the gas comprises predominantly (more than 50 vol%) nitrogen, carbon dioxide, or water vapor. Particularly preferably, the gas comprises less than 1 vol%, preferably less than 0.1 vol%, of oxygen.

[0049] In a further embodiment of the invention, a metal with an electronegativity of less than 1.8, preferably less than 1.7, is selected as the reducing agent. This ensures reliable reduction of the trivalent iron.

[0050] In a further embodiment of the invention, a metal with a lower (more negative) standard potential than that of iron is selected as the reducing agent.

[0051] In a further embodiment of the invention, a metal selected from the group comprising aluminum, zinc, magnesium, and calcium is used as the reducing agent. These metals have proven suitable for various reasons. Firstly, these elements are not harmful in the finished cement product, but are usually present anyway. Secondly, they, such as aluminum, are readily and inexpensively available. Furthermore, these metals are particularly well suited to the process according to the invention.

[0052] In a further embodiment of the invention, 0.01 to 1 mol of reducing agent is added per kg of added mineral material. In a further embodiment of the invention, the amount of reducing agent is selected such that the electrons released by the oxidation of the metal correspond to 0.03 to 0.33 times the amount of Fe contained in the mineral material. 3+ Theoretically, it would be sufficient to convert one-third of all iron atoms to divalent iron, forming magnetite. However, it has been shown that even 10% results in a decolorization that leads to an acceptable product. Thus, product optimization (from acceptable to optimal) against costs (the fewer, the cheaper) is possible in this range, depending on the targeted market.

[0053] In a further embodiment of the invention, the reducing agent is added with a particle size of less than 100 pm. Preferably, the reducing agent is added with a particle size of more than 0.1 pm.

[0054] In a further embodiment of the invention, the reducing agent is introduced by abrasion of grinding media. Aluminum grinding media are preferably used for this purpose. This is preferred when the required amount of reducing agent is small, i.e., particularly for low-iron clays.

[0055] In a further embodiment of the invention, the reducing agent is selected from the group comprising tin(II) sulfate (ZnSC), antimony trioxide (Sb20s), iron(II) sulfate (FeSC), iron(II) sulfate monohydrate (FeSC·H2O), and iron(II) sulfate heptahydrate (FeSC·H2O). Particularly preferably, the reducing agent is selected from the group comprising tin(II) sulfate (ZnSC), antimony trioxide (Sb20s).

[0056] In a further embodiment of the invention, elemental carbon is selected from the group comprising coal, graphite, anthracite, soot or petroleum coke in the presence of carbon dioxide as the reducing agent.

[0057] In a further embodiment of the invention, elemental carbon is used as the reducing agent, selected from the group comprising coal, graphite, anthracite, soot, or petroleum coke, in the presence of carbonates from the group comprising dolomite, magnesite, calcite, aragonite, iron carbonate, or alkali carbonates. In a further embodiment of the invention, the process comprises a control loop, wherein the amount of reducing agent added is controlled. The amount of reducing agent added is therefore actively controlled. The Lab color value (also CIELAB or L*a*b*) is determined from the activated material produced by the process. For the Lab color value, the brightness value L* is perpendicular to the color plane (a*,b*) and is standardized by EN ISO 11664-4 "Colorimetry - Part 4: CIE 1976 L*a*b* Color space." The amount of reducing agent added is increased if the a* value exceeds 3 and reduced if the a* value falls below 1.This optimizes the product for market acceptance and minimizes the consumption of reducing agents. Active control also enables optimal adaptation to the typically fluctuating composition of natural clays, for example.

[0058] In a further embodiment of the invention, the process comprises a control loop, whereby the added amount of reducing agent is controlled. Thus, the added amount of reducing agent is actively controlled. The Lab color value (also CIELAB or L*a*b*) is determined from the activated material produced by the process. For the Lab color value, the brightness value L* is perpendicular to the color plane (a*,b*) and is standardized via EN ISO 11664-4 "Colorimetry -- Part 4: CIE 1976 L*a*b* Color space." The added amount of reducing agent is increased if the color index is determined as the square root of the sum of (a*). 2and (b*)2 is greater than 5, preferably greater than 10. Accordingly, the amount of reducing agent added is reduced, provided that the color index is determined as the square root of the sum of (a*) 2 and (b*)2 is less than 10, preferably less than 5.

[0059] In a further embodiment of the invention, partial thermal activation is carried out prior to the mechanochemical activation. The thermal activation is preferably carried out at a temperature of less than 600°C, particularly preferably less than 500°C. For purely thermal activation, temperatures of, for example, 900°C are common. This allows energy savings and thus at least some of the energy required for the mechanochemical activation. Furthermore, reducing the maximum temperature also has other positive effects, for example, reducing the thermal formation of nitrogen oxides or avoiding unwanted product changes, such as color changes due to oxidation of color-imparting components.

[0060] In a further aspect, the invention relates to a binder which is produced by the process according to the invention.

[0061] The method according to the invention is explained in more detail below using an embodiment shown in the drawings.

[0062] Fig. 1 Flowchart

[0063] The process is shown in a highly schematic form in Fig. 1. Clay is taken from a clay deposit 10 as a mineral material for activation and color optimization. This material is passed through a sensor for chemical analysis 20 to determine the Fe content. 3+ to determine. The determined Fe 3+The aluminum content is transmitted to a control unit 70. The control unit 70 regulates the dosage of aluminum from an aluminum storage facility 30 to the clay. The clay-aluminum mixture is transferred to a first high-energy mill 40, where it is ground and both activated and, within the process, color-optimized simultaneously. The material emerging from the first high-energy mill 40 is analyzed in a color analysis 50, the L*a*b* color value is determined, and this value is transmitted to the control unit 70. The finished product is transferred to a product storage facility 60.

[0064] Alternatively, instead of chemical analysis 20, a further color analysis corresponding to color analysis 50 can be used. This can simplify the process considerably. The color value of the tone is used and, based on experience, a Fe 3+ -content. This means that the procedure can otherwise be carried out unchanged.

[0065] Reference symbol

[0066] 10 Clay deposits 20 Chemical analysis

[0067] 30 aluminum bearings

[0068] 40 first high-energy mill

[0069] 50 color analysis 60 product warehouse

[0070] 70 Control unit

Claims

Patent claims 1. A method for the mechano-chemical activation and simultaneous color optimization of mineral material, characterized in that the mechano-chemical activation and simultaneous color optimization take place in a first high-energy mill (40), wherein the mineral material is ground together with a solid reducing agent in the first high-energy mill (40), wherein the mechano-chemical activation of the mineral material causes an increase in the R3 value (7d) according to ASTM C1897-20 by at least 150 J / g, preferably by at least 250 J / g.

2. Process according to claim 1, characterized in that a metal having an electronegativity of less than 1.8 is selected as the reducing agent.

3. Process according to one of the preceding claims, characterized in that a metal with a lower (more negative) standard potential than that of iron is selected as the reducing agent.

4. Process according to one of the preceding claims, characterized in that the reducing agent is a metal selected from the group comprising aluminum, zinc, magnesium and calcium.

5. Process according to one of the preceding claims, characterized in that 0.01 to 1 mol of reducing agent is added per kg of added amount of mineral material.

6. Method according to one of the preceding claims, characterized in that the amount of reducing agent is selected such that the electrons released by the oxidation of the metal correspond to 0.03 times to 0.33 times the amount of Fe contained in the mineral material. 3+ corresponds.

7. Process according to one of the preceding claims, characterized in that the reducing agent is added with a particle size of less than 100 pm.

8. Process according to one of claims 1 to 6, characterized in that the reducing agent is supplied by abrasion of grinding media.

9. The method according to claim 1, characterized in that the reducing agent is selected from the group comprising tin(II) sulfate (ZnSC), antimony trioxide (Sb2O3), iron(II) sulfate (FeSC), iron(II) sulfate monohydrate (FeSC ■ H2O), and iron(II) sulfate heptahydrate (FeSC ■ 7 H2O).

10. A process according to claim 1, characterized in that elemental carbon is selected as the reducing agent from the group comprising coal, graphite, anthracite, soot or petroleum coke in the presence of carbon dioxide.

11. A process according to claim 1, characterized in that elemental carbon is selected as the reducing agent from the group comprising coal, graphite, anthracite, soot or petroleum coke in the presence of carbonates from the group comprising dolomite, magnesite, calcite, aragonite, iron carbonate or alkali carbonates.

12. Method according to one of the preceding claims, characterized in that the method comprises a control circuit, wherein the added amount of the reducing agent is controlled, wherein the L*a*b* color value is determined from the activated material produced by the method, for example, wherein the added amount of the reducing agent is increased if the a* value exceeds 2 and wherein the added amount of the reducing agent is reduced if the a* value falls below 1.

13. Method according to one of the preceding claims, characterized in that a partial thermal activation is carried out before the mechano-chemical activation.

14. Binder prepared by the process according to any one of the preceding claims.

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